We pick l.root-servers.net, one of the 13 root servers (1), and ask it about www.sbobet168.com and learn that com is delegated to 13 name servers (2), so we ask d.gtld-servers.net where we learn that sbobet168.com is delegated to two name servers, including pdns01.domaincontrol.com (3), so we ask that one where we see a CNAME from www.sbobet168.com to sbobet168.com, so we have to start all over again. We already know that pdns01.domaincontrol.com is authoritative for sbobet168.com (4) and ask it about sbobet168.com and get the following answer: